This study aims to investigate the possibility of additional value of leukotriene receptor antagonist (LTA) on dyspnea score, arterial blood gases (ABG), pulmonary function tests (PFTs), and quality of life (St. George QoL) in chronic obstructive pulmonary disease (COPD) patients. In this randomized, prospective, single-blind, and controlled study, 117 non-reversible COPD patients defined by global initiative for chronic obstructive lung disease (GOLD) criteria were randomized to receive ipratropium bromide, formoterol and montelukast (n:58, montelukast group) or ipratropium bromide and formoterol (n:59, control group) after a 2-week run-in period. There was no significant demographic difference between the two groups (P>0.05). Baseline ABG, PFT, visual analoque scores (VAS), and QoL scores were obtained and at first month and second month, PFT, VAS, and QoL scores were repeated and ABG was obtained at second month and the values were compared with baseline values. As the result of the comparison, there was significant increase in vital capacity, FVC, FEV1, VAS, and PaO2 parameters (P<0.05), and a significant decrease in the QoL scores (P<0.05) in the montelukast group. These parameters did not show any difference in the control group (P>0.05). Sputum samples that could be obtained in 24 of the COPD patients were evaluated and in the montelukast group, there was a decrease in neutrophilic activity after treatment (n:13) (P:0.059). These results suggest that LTA that is used additionally in routine treatment protocol can produce additive improvement on PFT, dyspnea score and especially QoL in patients with stable COPD and for these reasons, LTA may be taken into account when there is need for an additional anti-inflammatory treatment in COPD patients.